Re: [PATCH for-next 2/2] RDMA/hns: Add NOP operation for sending WR

[Wenpeng Liang <liangwenpeng@huawei.com>]

On 2022/4/7 21:20, Jason Gunthorpe wrote:
> On Thu, Apr 07, 2022 at 09:14:03PM +0800, Wenpeng Liang wrote:
>> From: Yangyang Li <liyangyang20@huawei.com>
>>
>> The NOP operation is a no-op, mainly used in scenarios where SQWQE requires
>> page alignment or WQE size alignment. Each NOP WR consumes one SQWQE, but
>> the hardware does not operate and directly generates a CQE. The IB
>> specification does not specify this type of WR.
>>
>> Signed-off-by: Yangyang Li <liyangyang20@huawei.com>
>> Signed-off-by: Wenpeng Liang <liangwenpeng@huawei.com>
>> ---
>>  drivers/infiniband/hw/hns/hns_roce_hw_v2.c | 9 +++++++++
>>  drivers/infiniband/hw/hns/hns_roce_hw_v2.h | 9 +++++++++
>>  2 files changed, 18 insertions(+)
> 
> Where is it used?
> 

This function has a precondition. The driver needs to provide two interfaces
to the user, one interface is used to fill the wqe, and the other is used to
ring the doorbell. If the content of the wqe is repeated, then the user does
not need to fill this wqe again but directly rings the doorbell.

If the user's wqe used to complete the specified work request does not fill
the send queue, then the user can fill the remaining wqe in the send queue
as a NOP operation.

This feature requires some cooperating code and does not meet the upstream
conditions. Therefore, I will revoke this patch.

Thanks,
Wenpeng

> Jason
> .
>